(1) Field of the Invention
The present invention relates to a small-size light-weight light attenuator to be used for adjustment of the quantity of light in a light transmission line, measurement of the light transmission characteristics and other tests, and to a process for the fabrication of this light attenuator.
(2) Description of the Related Art
As the conventional light attenuator arranged in a light transmission line composed of optical fibers, the light attenuators shown in FIGS. 10 through 12 are known.
In the light attenuator shown in FIG. 10, an optical fiber 91 is arranged on the central axis of a ferrule 93 to construct a light connector plug and an optical fiber 92 is arranged on the central axis of a ferrule 94 to construct another light connector plug, both ferrules 93 and 94 are arranged within a sleeve 95 while confronting each other, and lenses 96 and 97 for adjusting the optical axis and a light-attenuating element (such as a filter) 98 are arranged between the ferrules 93 and 94.
In the light attenuator shown in FIG. 11, an optical fiber 101 is arranged on the central axis of a ferrule 103 to construct a light connector plug, and an optical fiber 102 is arranged on the central axis of a ferrule 104 to construct another light connector plug, both ferrules 103 and 104 are arranged within a sleeve 105 while confronting each other, and a cylindrical member 108 having an optical fiber rod 107 arranged on the central axis thereof is interposed between the ferrules 103 and 104. An inclined face is formed on one end face of the cylindrical member 108, and a light-attenuating film 106 composed of a vacuum-deposited metal film is formed on this inclined face. The light attenuator of this type is illustrated, for example, in Japanese Unexamined Patent Publication No. 59-79402.
In the light attenuator shown in FIG. 12, a light-attenuating film 113 composed of a vacuum-deposited metal film is formed on the end face of one of optical fibers 111 and 112 arranged to confront each other, and the end faces of the confronting optical fibers are fusion-bonded to each other by arc discharge generated by electrodes 114 and 115. The light attenuator of this type is illustrated, for example, in Japanese Unexamined Patent Publication No. 55-79402.
Nevertheless, a high degree of skill and experience is necessary for the fabrication of these conventional light attenuators, and moreover a large-scale equipment is required for such a fabrication. Accordingly, these conventional techniques disadvantageous in that it is very difficult or impossible to increase the operation efficiency or carry out a mass production thereof.